Denmark (; ) is a country in Northern Europe. The most southern of the Nordic countries, it is located southwest of Sweden and south of Norway, and bordered to the south by Germany. The Kingdom of Denmark is a sovereign state that comprises Denmark and two autonomous constituent countries in the North Atlantic Ocean: the Faroe Islands and Greenland. Denmark proper has an area of , and a population of 5,659,715 (January 2015). The country consists of a peninsula, Jutland, and the Danish archipelago of 443 named islands, of which around 70 are inhabited. The islands are characterised by flat, arable land and sandy coasts, low elevation and a temperate climate. A Scandinavian nation, Denmark shares strong cultural and historic ties with its overseas neighbours Sweden and Norway. The national language, Danish, is very closely related and mutually intelligible with Swedish and Norwegian. The unified kingdom of Denmark emerged in the 10th century as a proficient seafaring nation in the struggle for control of the Baltic Sea. Danish rule over the personal Kalmar Union, established in 1397 (over the Norway and Sweden), ended with Swedish secession in 1523. However, Denmark still kept a union over Norway which lasted until its dissolution in 1814. Denmark inherited an expansive colonial empire from this union, of which the Faroe Islands and Greenland are remnants. Beginning in the 17th century, there were several cessions of territory; these culminated in the 1830s with a surge of nationalist movements, which were defeated in the 1864 Second Schleswig War. Denmark remained neutral during World War I. In April 1940, a German invasion saw brief military skirmishes while the Danish resistance movement was active from 1943 until the German surrender in May 1945. An industrialized exporter of agricultural produce in the second half of the 19th century, Denmark introduced social and labour-market reforms in the early 20th century, making the basis for the present welfare state model with a highly developed mixed economy. The Constitution of Denmark was signed on 5 June 1849, ending the absolute monarchy which had begun in 1660. It establishes a constitutional monarchy—the current monarch is Queen Margrethe II—organised as a parliamentary democracy. The government and national parliament are seated in Copenhagen, the nation’s capital, largest city and main commercial centre. Denmark exercises hegemonic influence in the Danish Realm, devolving powers to handle internal affairs. Denmark became a member of the European Union in 1973, maintaining certain opt-outs; it retains its own currency, the krone. It is among the founding members of NATO, the Nordic Council, the OECD, OSCE, and the United Nations; it is also part of the Schengen Area. Danes enjoy a high standard of living and the country ranks highly in numerous comparisons of national performance, including education, health care, protection of civil liberties, democratic governance, prosperity and human development. Denmark is frequently ranked as one of the happiest countries in the world in cross-national studies of happiness. The country ranks as having the world’s highest social mobility, a high level of income equality, has one of the world’s highest per capita incomes, and has one of the world’s highest personal income tax rates. A large majority of Danes are members of the National Church, though the Constitution guarantees freedom of religion.